Automatic knife



FIG. 1 is a perspective view of an automatic knife incorporating my new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a bottom plan view thereof;

FIG. 4 is a right side view thereof;

FIG. 5 is a left side view thereof;

FIG. 6 is a rear elevation view thereof; and,

FIG. 7 is a front rear elevation view thereof.

The straight, connecting broken lines across the front, back, and two sides of the automatic knife indicate the boundary of the claim. All other broken lines in the drawings are directed to environment and from no part of the claimed design. 

The ornamental design for an automatic knife, as shown and described. 